Heating control system



June 18, 1946. H. E. MALONE HEATING CONTROL SYSTEM Filed Dec. 20, 1941 3Sheets-Sheet l INVENTOR. HUMER E.MALUNE BY WW1 ATTORNEY June 18, 1946.MALONE 2,402,174

HEATING CONTROL SYSTEM Filed Dec. 20, i941 s Sheets-Sheet 2 INVENTOR.HUMER E MAL EINE June 18, 1946. H. E. MALONE HEATING CONTROL SYS TEMFiled Dec. 20, 1941 3 Sheets-Sheet 3 4 z fin 0 .M m I Z m w w l 0 w I 0Patented June 18, 1946 UNITED STATES PATENT OFFICE HEATING CONTROLSYSTEM Homer E. Malone, Milwaukee, Wis., assignor to Perfex Corporation,Milwaukee, Wis a corporation of Wisconsin Application December 20, 1941,Serial No. 423,723 9 Claims. 01. lie-+161),

1 This invention relates in general to automatic control for heatinsystems, and is more particularly concerned with control of solid fuelburner devices.

In domestic heating it has become common to mploy automatic stokers as asource of heat. A stoker of this type is usually controlled by means ofa room thermostat which serves to start and stopthe stoker in amanner-to maintain a constant temperature within the building. It hasalso become common to provide some sort of holdfire device for operatingthe stoker independently of the room thermostat for keeping the firealive. In spite of these holdfire devices th fire sometimes goes out.When this occurs and the room thermostat next calls for heat, the stokerwill be operated to deliver coal to the retort. Due to the .fire beingout, this coal merely accumulates within the combustion chamber, withpossible injury to the furnace. In any event, this accumulation ofunburned coal within the combustion chamber makes rebuilding of the firea difficult task. In order to avoid the difiieulty above mentioned,outfire controls have been provided which are intended to preventoperation of the stoker if the fire goes out. Prior to the presentinvention, this type of control consisted merely of a thermostaticdevice responsive to the temperature of the gases passing through thestack and arranged to open a switch in the stoker circuit when the stacktemperature falls to a point indicating the fire is probably out. Themain difficulty with such temperature responsive outfire controls isthat of obtainin a proper adjustment. If the control is set to open itsswitch at too low a temperature, it is possible that the switch will notopen until a long time after the fire goes out. On the other hand, ifthe control is set to open at too high a temperature, it is likely thatthe switch will open and prevent operation of the stoker, even though asmall fire is present. Thus the control, instead of protecting againstopera-v tion of the stoker without a fire, actually puts the fire out.

The primary object of this invention is to provide a control for astoker which is simple and dependable in operation and which places thestoker out of operation if the fire should go out. This result isobtained by arranging the outfire control so as to respond to the amountof coal in the combustion chamber. As long as the stoker is functioningproperly and combustion is prescut, the quantity of coal will berelatively low. However, when the fire goes out and the stoker operates;an abnormal amount of coalwill acing this. function.

cumulate in the combustion chamber. The outfire control of the presentinvention responds to this abnormal quantity of coal and serves toprevent iurther operation of the stoker.

An object of the present invention, therefore, isthe provision of anoutfire control which responds to'the quantity of coal in the combustionchamber, and which places the stoker out of operation when this quantityincreases to a value indicatin that the fire is probably out.

In the preferred embodiment of this invention, the quantity of coal inthe combustion chamher is measured by its level within the combustionchamber. Whilethis measurement of coal level may be made in variousmanners without departing from the invention, this measurementpreferablyis made by means of a device which over-' lies the coal in thecombustion chamber and which .is contacted by the coal and urgedupwardly when the coal level risesto a point indicating that the fire isprobably out, this upward movement serving to actuate a control devicefor stopping the stoker.

It is 'a'further object of the invention to providean arrangement forraising this overlying device for permitting an attendant to work on thefirst without: danger of damage to the device. This feature incidentallyprovides for stopping of the stoker at thistimaand thus dispenses withthe necessity of a separate line switch for provid- It. is afurtherobjectof the invention to provide-:anarrangement by which the overlyingdevic is held in its raised position when the access door is open andwhich is returned automatically toward normal position upon closure ofthe access door.

A further object of the invention consists of the provision of anoutfire control of the type generally described which serves to placethe stoker out of operation when the access door for the furnaceisopened and which automatically renders the stoker operative when theaccess door is closed.

Further objects of the invention consist of various novel details ofconstruction and will become apparent from the followin description andthe appended claims.

While the invention is primarily intended as an outfire. control forstokers, certain aspects of th invention are of broader application.

Fora full disclosure of the present invention, reference is made to thefollowing detailed description'and tothe accompanyin drawings, in whichrFig. 5 is a side view, partly in section, of ani other form of theinvention;

Fig. 6 is a front view of the embodiment of Fig. 5;

Fig. 7 is a top view, partly in section, of this same embodiment of theinvention;

Fig. 8 is a side view partly in section showing still another embodimentof the invention;

Fig. 9 is a top view of the device shown in Fig. 8; and

Fig. 10 is a front view of this same device.

Referring first to Fig. 1, reference character I indicates a furnaceprovided with a stoker 2 which may be of usual, construction. Stoker 2.may include a hopper 3 and an electric motor 4 which operates a fuelfeeding means or feed screw 5 through suitable mechanism, not shown.This motor 4 also operates an air feeding means or fan 3 which deliversair to the stokerretort through an air duct 1. The motor 4 is controlledby means of a relay generally indicated as 8, this relay having a coil 9which actuates, through a suitable armature,,a switch arm l0 cooperatingwith a contact This relay may be controlled in accordance with thedemand for heat by means of a room thermostat l2 and receives power fromthe secondary l3 of a transformer it, this transformer it having aprimary coil |6 which is connected across line wires H and I8. When theroom thermostat calls for heat it closes its contacts i9, thusenergizing relay coil 9, which causes the switch arm ||l to engagecontact II. This completes a circuit from theline wire ll through wire23, switch arm l0 and wire 2| to the outfire control 22, and fromcontrol 22 through wire 23 to motor 4 which is connected to line wire Itby wire 24. The outfire control will be described in detail, andincludes. a switch which remains closed as long as the level of fuel inthe combustion chamber is below a predetermined point. However, if thefire goes out, the coal level builds up in the combustion chamber to apoint at which the outfire control 22 breaks the motor circuit, whichprevents further operation of the motor.

The control system preferably also includes a suitable holdfire control.This control may consist of a timer formed of a synchronous motor 25which operates a cam 26 for actuating a switch 21 connectedin parallelwith the thermostat l2.

The control system may also include a suitable alarm 28, such as a lightor bell, this alarm being energized by a switch of the outfire control22 which is moved to closed position when the outfire control breaks thecircuit of stoker motor 4,

Referring now to the construction of the outfire control 22', referenceis made to Figs. 2, .3 and 4. This control may consist of a base 30provided with out-turned ears 3| and 32 at its upper and lower endsrespectively. This base may be secured to the furnace or to a suitablebracket mounted thereon by means of screws 33. The upper ear or flange3] is preferably provided switch arm 5 l.

with openings 34 and 35 for the reception of suitable electric wiringfittings for the stoker motor wires 2| and 23 and the alarm wires 36 and31 (Fig. 1). Preferably a barrier 38 is mounted on the base 30 andextends outwardly therefrom so as to prevent improper wiring of thecontrol.

Mounted on the base at the right hand side of barrier 38 is a. switchblock 39 formed of insulating material. This block is formed to carry anupper terminal bracket 40 having a terminal screw 4| for the attachmentof one of the stoker motor wires. This bracket 40 is provided with aturned up portion 42 which receives a contact stud 43. A similarterminal bracket 44 is mounted on the lower end of switch block 39, thisterminal bracket having a terminal screw 45 and a turned up portion 46which receives a second contact stud '61. The contacts 43 and 4! areadapted to be bridged by means of a flexible contact bar 58 whichcarries a pair of movable contacts, one adapted to engage the fixedcontact 43 and the other adapted to engage the fixed contact 47. Theflexible contact bar 48 is attached to a rigid bar 49, which bar ispivoted to a pivot pin .50 which is carried by a main The main switcharm 5| also carries an armature member 52. This armature member consistsof a portion 53 which is arranged to cooperate with a permanent magnet54 mounted on the switch block 39. The portion 53 ofthe armature memberis attached to the main switch arm 5| by an in-turned portion 55 andalso carries an earl-56 which extends to the pivot pin 5i} forsupporting the outer end thereof. The permanent magnet 54 is adjustablysecured to the block'39'by means of a screw 51. A second switch block 60is mounted on the base 30 on the left hand'side of barrier 38. Thisswitch block 50 may be identical with the switch block 39 and carriesfixed contact studs 6| and 62 which cooperate with movable contacts 63and 64 carriedbythe main switch arm 5|. The block 60 is also providedwith a permanent magnet 65 which cooperates with an armature 66 carriedby the main switch .arm 5|.

From the description thus far it will be apparent that when the switcharm 5| is in the position shown, the fixed contacts 43 and 4? arebridged by the movable contacts and the movable contact arm, the fixedand movable contacts-being held in firm engagement by the permanentmagnet 54 which attracts armature 53. This bridging of fixed contacts 43and 4'! joins wires 2| and 23 (Fig. 1) and thus permits operation of thestoker. At this time the movable contacts 63 and 54 are disengaged fromtheir respective fixed contacts BI and 62. Consequently wires 36 and 31(Fig. 1) are discon nected and the alarm device 28 is deenergized. Theposition of the main switch arm 5| as shown in Fig. 2 is the normalposition for this switch arm, this position permitting operation of thestoker and causing the alarm device 28 to remain deenergized.

Referring now in detail to the main switch arm shaped bracket 16, thisbracket having spaced legs 11 and 18 (shown. dotted), these legs'beingjoinedvby an intermediate portion 19 (Fig. 4). supporting the pivot 'pinI3 and lying under the lower'portion Ii of-the switch arm 5|. The legs1'! and 18 are provided with out-turned portions and are secured to thebase 39 by screws 89-.

Secured to the base 39 near its lower end is. a U-shaped bracket 8|.having outwardly extending legs 82 and 83.: This bracket may be attachedto the base 39 by screws 84. The cars 82- and 83 are provided withsuitably aligned openings for receiving a shaft 86. This shaft 86 isbent at 81 so as to provide an inwardly extending portion 88-which isadapted to extend through the access opening of the furnace into thecombustion chamber and over the coal therein. The other end of the shaft86 carries a suitable manual operator for permitting the overlyingportion 88 to. be raised. This manual operator may consist of a collar89 which fits over the end of shaft 86, this collar receiving a handleportion 99 having a threaded end cooperating with thread in the collarfor locking the collar in place on shaft 86. The handle portion 99preferably extends outwardly from the controljas shown. By pressingdownwardly on the handle 99 the shaft 86 may be rotated so as to raisethe overlying portion 88 upwardly, thus moving this ,portion out of theway so that it will not be injured when the attendant is working on thefire. Preferably means are provided for holding the overlying portion 88in raised position while the access door 9| on the furnace is open. Thismeans may comprise a latch member 92'. This latch member is of generalU- shaped construction, having legs 93 and 94 which are secured to pins95 and 96 in turn secured to ears formed on the bracket 8 I. This latchmember is provided with an operating portion 91 which extends outwardlyfrom the control housing so as to be actuated by the access door 9|. Thelatch member 92' is provided with a recess 98 which is adapted toreceive a pin 99 which is secured to a collar I99. This collar extendsbetween the ears 82 and 83 of the bracket 8| and surrounds the shaft 86.The collar I99 is also rigidly secured to the shaft 86 either by adriving fit or by suitable securing means. The latch member 92 is biasedin a counterclockwise direction a seen in Fig. 4 by means of a springIN, the fixed end of which is secured to the leg I1 of the U-shapedbracket 16. It will be apparent that when the access door 9| is closedthe latch extension 91 will be engaged thereby, this pressing theextension inwardly against the action of spring |9| and retracting thelatch recess 98 so that the pin 99 is free to move. When the access door9| i open, however, the spring I9I is free to urge the latch member 92to the position shown in dotted lines in Fig. 4. Consequently when theshaft 86 is rotated for raising the overlying portion 88, the .pin movesdownwardly until'it is opposite the recess 98, at which time the springI9I rocks the latch member so that the recess 98' slips over pin 99. Nowwhen the handle portion 99 is released, the overlying portion 88 will beretained in its upper position as the upper surface of pin 99 willengage the upper surface of recess .98. The overlying portion 98 willthus be retained in its upper position until the access door 9| isclosed, at which time the latch extension 91 is pressed inwardly,

this rocking the edges of decess 98 away from pin-.99, thereby releasingpin 99. The overlying,

portion 88 now drops by its own weight to its normal position whereinthe pin 99 engages the top of the largeslot I92 formed in the latchmember. It will be noted that the pin 99 cooperates with the upper andlower surfaces of the large slot I92 in the latch member for providinglimits of movementof shaft 86. Thus engagement of pins 99 with the topof the large slot determines the lower limit of movement for theoverlying-portion 88, while the pin 99 and the lower surface of slot I92cooperate in determining the upper limit of movement of the overlyingmember 88.

The switch arm 5| is rocked about its pivot 13 by rotary movement ofshaft 86. This result is obtained by means of a flexible arm I95. whichis attached to a suitable bracket I formed on the lower portion 14 ofthe switch arm bracket II. The left hand end of the flexible arm I95 isadapted to cooperate with spaced lug I96 and I91 formed on a bracket I88which is attached to the collar member I99.

From the foregoing description it will be apparent that when the stokeris in normal operation, the switch arm 5| will be in the position shownwherein fixed contacts 43 and 4! are bridged, which completes thecircuit to the stoker motor. At this time the fire or fuel level in thecombustion chamber is below the level of the overlying device 88, thislevel being determined by the engagement of pin 99 with the top surfaceslot I92. The access door at this time of course will be closed, whichrestrains the latch member 92 from rotation b spring |9|. If the fireshould go out, continued operation of the stoker will feed coal into thestoker retort, thus causing a rise in level of the coal in the fire pot.This rising coal will engage the overlying portion 88, thus urging itupwardly, this causing rotation of the shaft 86 for moving the lug I99downwardly into engagement with the flexible arm I95. Due to the actionof the permanent magnet 54 in attracting armature 53, the movablecontacts will be held in engagement with the fixed contacts 43 and 41until the lug I96 in deflecting the spring member I95 stores suiiicientstress in this spring member to overcome the holding force of the magnet54. At this time the switch arm 5| will move with snap action in acounter-clockwise direction about its pivot. thereby causing .thestationary contacts 43 and 41 to become unbridged and causing thestationary contacts 6| and 62 to become bridged. Thus the stoker isplaced out of operation and the alarm device 28 is energized. The devicewill remain in this position until the excess coal is removed from thefire pot.

When the attendant desires to remove clinkers from the fire or torebuild the fire, he opens the access-door 9|, which releases the latchmember 92. He also depresses the handle 99 downwardly, which causes theoverlying member 99 to be raised a substantial distance from the fireand out of the way. During this movement, the lug I96 engages theflexible arm or spring blade I95 which causes movement of the switch arm5| for unbridging the contacts'43 and 41, this stopping the stoker motorif it should happen to be running at this time. Also this downwardmovement of handle 99 results in downward movement of the pin 99 to apoint where it coincides with the slot 98. Due to'the latch member 92now. being released by the access door being open,, the.spring |9|rotates this latch member so as to cause slot 98 to retain the pin 99 inits member H receives a handle. Ill.

lower; position. Thus: the overlyingmember 88: is retainedin an out-of-the-wayrpositionand the circuit to the stokcr motor is. broken duringthe, time that the attendantworkson.thefire. When. the access dooriscloseditengagies the, actuating. member 91. of thelatch. 92; thusmoving: this ,latch to a position in whichthe slot 98': releases pin99', the overlying member 83 now dropping by its own weight to itslowerposition; At this time the-lug I815 engages the flexible member I85 forurging theswitch arm 5 I in a clockwise direction about its pivot, this:unbridging the stationary contacts 6| and 62 with snap action. and. alsobridging stationary contacts 43 and 4 with snap action. Thus closure ofthe access door auto matically returns the control to operativeposition, deenergizing theal'arm device 28 and permitting operation ofthe stoker motor.

Figs. 5, 6 and 7 Referring now to Figs. 5. Band '7; these figuresillustrate a different embodiment of the invention. This device mayconsist of a base I IIJ'which may be a cup-shaped stamping, this basereceiving a cover III. A shaft II2 extends through thesides I l3iand II4.of the base, this shaft having its left handend fitting into a collarmember I I5 which in turn fits in an enlarged opening I16 formed in theside IM of the base. This. collar The other end of the shaft I I2 isbent to form an overlying member I I9 which is adapted to extendinwardly through the access door of a furnace and overlie the fuel inthe fire pot. This overlying member Il9, if, desired, may be providedwith a suitable heat resisting cover I29 so as to. prolong the lifethereof. The collar member H5 also receives a stud I2I which may securethismember to shaft II2. The stud I2I also cooperates with a spring clipI22 for holding the overlying member in its raised position. It will beapparent that when the handle II! is depressed for raising the overlyingportion II'Q, the stud I21 will be rotated clockwise so as to engage thedepression I23 formed in the spring clip I22. The overlying member I I9is thus held in its raised position until the handle portion HT ispulled upwardly, this causing the spring clip I23 to yield and permitreturn movement of the member II 9 to its normal position.

The shaft I I2 near the center of base IIO: carries a second collarmember I24. This collar member is formed with a pair of abutments I25and I26 which are adapted to engage the base H8 and form stops forlimiting rotation of shaft II2. Thus the abutment I25 by engaging thebase IIU limits counterclockwise rotation of the shaft H2 andconsequently determines the lower or normal position of the overlyingmember II9 within the fire box. The abutment I26 in engaging the basdetermines the upper limit of movement of th overlying member I I9. Theside of the collar I24 which faces outwardly from thebase is providedwith a generally arcuate surface I21 for a purpose which will becomeapparent as this description proceeds. Located on each side of thecollar I24 are spacing, members I28 and I29 These members provide forproper spacing of legs I30 and. I3I of a, mercury switch carriergenerally indicated as I32. This carrier may consist of a pair ofU-shaped clamping members I33 and I34 the member I33 being formed withthe leg I30, and the. member I34 being formed with the, leg. I3.I, theselegs being pivot- .ally mounted on shaft H12 as shown. The mercuryswitchcarrier I32: receives a mercury switch I36. This mercury switch atits left hand end carries a spring I31 which engages the arcuate surfaceI'2l, of the collar member 12.4; this, providing a slip friction drivebetween shaft I I2, and the mercury switch. The mercury switch I35preferably is. of. the metalliccasi-ng type and extends through a slotI38in the cover so that it may be operated manually. This switch isarranged with its electrodes at its left hand end, having leads I39 andI40 attached to suitable terminals I II and I42 carried by a terminalbracket I43 which is mounted on the base III! by screws I44 and spacersM5.

During normal operation of the stoker theoverlying member I I9 is notcontacted by. thecoal in the fire pot and thus drops by. its own weightto a normal position which is determined by the abutment I25 engagingbase III]. The normal position of the mercury switch I36 is indicated bythe upper dotted lines, this causing the mercury within the switch tobridge the switch electrodes for completing a circuit to the stokermotor. If the fire goes out, the coal level in the fire pot rises, thisengaging the overlying member I I9 and moving. it upwardly, thusrotating the shaft H2 in a clockwis direction as seen in Fig. 5. Thisrotation of shaft II-2- by engagement of the circular surface I21 of thecollar member I24 with the spring I31 causes tilting of th mercuryswitch I36 so. as to unbridge its electrodes and break the circuit to thStoker motor. The stoker motor thus remains out ofoperation until thefire isrekindled.

It will be noted that due to the slip friction drive for the mercuryswitch I36, this switch may be tilted independently of the position ofthe arm H9. The switch I36 thus may be used as a manual switch forpreventing operation of the stoker, for example during the summer. Theswitch I36 may be also employed for preventing operation of the stokerwhen the fire is being given attention. Thus the attendant may eitherpress the mercury switch to its lowermost position for stopping the,stokcr, or he may depress the handle II! for raisin the overlyingportion II9 out of the way, this automatically shifting the switch I36to its lower position by means of the slip friction drive abovedescribed. It should be noted that due to this slip friction drive, themercury switch I36 is always returned to its upper position whenever thehandle HT is actuated for shifting the overlying member I I9 downwardlytoward normal position.

It will be apparent that by adjusting the CO1?- lar member I25 on shaftI I2 the lower or normal position of th member Il9v may be varied formeeting the needs of different installations. Similarly by adjusting thecollar member II5 on shaft I I2 the upper position of member II9 may bevaried to suit the needs of the particular installation.

Figs. 8, 9 and 10 Referring now to Figs. 8, 9- and 10, these figuresshow an embodiment of the invention wherein the control is mounteddirectly upon the access door of the furnace. In. this device a base Irof insulating material is mounteddirectly upon the access door I5I, thisbase being provided with a cover I52. The control in this case may bewired from a junction box I53. secured to the furnace jacket by means offlexible BX cable I54, which permits opening and closing of the accessdoor. The base l5fl: may be provided with a.

'9 bracket I55 which carries a pivot pin for a switch operatin arm I56which is formed of insulating material. This arm at its lower end isattached to a movable contact bar I51 which is adapted selectively tobridge either a pair of fixed contacts I58 and I56 or a pair of fixedcontacts I66 and IEiI. Thesestationary contacts are carried by suitablebrackets mounted on base member I55 as shown. The switch operating armI56 is provided at'its' upper end with a biasing' spring I62, thisbiasing the arm I51 in a direction tending to bridge the stationarycontacts I58 and I59;

The switch operating'member I56 is also pivoted to an operating stem I63which extends through coinciding openings in the base I50 and the accessdoor II. This operating stem is'provided at its inner end with anadjusting screw I64 which is adapted to be engaged by a lever arm I65 ofa'bell crank member which is pivoted at I66 to a bracket mounted on thetop of the access door frame. This bell-crank member includesanoverlying member I61 which overlies the coal in the combustionchamber. Th bell crank member is also provided with a stop memberI68which is adapted to engage the bracket for pivot I66'and thusdetermine the normal position 'of the member I61 in the combustionchamher. If desired, the stop member I68 may be made adjustable'by meansof a suitable adjusting screw.

The adjusting scr'ew- I64 on the stem' I63 is adjusted so that whenthe'access door I5I is closed and the bell crank member is in itsnormal' position as'shown, the screw I64 will engage the leverarm I65for urging the switch operating member I56 in a clockwise directionsufficiently to bridge the stationary contacts I 60 and I6I. This, asshown in Fig. 9, completes the circuit from wire I16 to'wire I12forpermitting operation of the stoker motor I13;

If the fire should go out the fuel level in the firepot will rise, thuscausing the fuelto engage the overlying member I61, rotating itclockwise about pivotI66 and retracting the lever arm I65 fromengagementwith adjusting screw I 64. This will permit the spring I62 to rotate theswitch operating arm I56 in a counter-clockwise direc tion, thusunbridging the stationary contacts I60 and IBI' for placing the stokerout of operation; This will also result in bridging of contacts I58and-159 for energizing the alarm device I14. While a suitable snapaction means has not been shown for sake of clearnessin this embodimentof the invention, it is preferable in actual practice to providesuch'means, for example as shown in Fig. 1. 1

It will be apparent that when the access door is opened the adjustingscrew I64 on the stem I63 is retracted from engagement with the leverarm I65. This permits the spring I62 to rock the switch operating memberI 56 for stopping the stoker motor. When the access door is moved backto closed position the adjusting screw I64 will again engage lever armI65 whereby to rock the switch operating member I56 toward normalposition for permitting stoker operation.

From the foregoing description it will be apparent that the presentinvention provides an outfire control for stokers which is simple inconstruction and positive in operation, this control stopping the stokeronly when the fire is actually out and always stopping the stoker atsuch time. It will be further apparent that the present inventionprovides an arrangement by which the outfire control serves to stop thestoker when the fire is being given attention, the stoker beingautomatically conditioned for operation when the access door is closed.While only a few possible embodiments of the invention havebeen'illustrated; it will be apparent that many changes may be made bythose skilled in the art without departing from the scope of theinvention. In addition, while the invention is primarily intended forcontrol of stokers, it will be apparent that certain features are ofbroader application. It is therefore desired to be limited only by thescope of the appended claims.

What is claimed is:

1. In a control system for a heating system having a stoker mechanismincluding fuel feeding means for feeding solid fuel to a combustionchamber and air feeding means for feeding air to the combustion chamber,the combination of, means responsive to, thedemand for-heat from thestoker mechanism for placing at least one of the feeding means into andout of operation, means including a controller for controlling at leastthe other of said feeding means, an access door for the combustionchamber for permitting manual tending of the fire, movable member meansextending from said controller and overlying the fuel in the combustionchamber, said movable member means actuating said controller inaccordance with the height of. the fuel in the furnace, and means forshifting said movable member means to a position in which it does notinterfere with manual tending of the fire when the access door is open;I r

-2. In a control system for a heating system having a stoker mechanismincluding fuel feedingmeans for feeding solid fuel to a combustionchamber and air feeding means for feeding air to the combustion chamber,the combination of, means responsive to the demand for heat from thestoker mechanism for placing at least one of the feeding means into andout of operation, means including a controller for controlling at leastthe other of said feeding means, an access door for the combustionchamber for permitting manual tending of the fire, movable member meansextending from said controller and overlying the fuel in the combustionchamber, said movable member means being constructed and arranged so asto be urged upwardly by the fuel and when raised above a predeterminedlevel actuating said controller to stop the feeding means controlledthereby, and means independent of the fuel for moving said movablemember means upwardly to at least said predetermined level and holdingsaid movable member means in such position when the access door is open.r

, 3. .In a control system for a heating system having a stoker mechanismincluding fuel feeding means for feeding solid fuel to a combustionchamber and air feeding means for feeding air to the combustion chamber,the combination of, a room thermostat responsive to the demand for heatfrom the stoker mechanism for placing at least one of said feeding meansinto and out of operation, an access door for the combustion chamber, aswitch for controlling the stoker mechanism, means for actuating saidswitch from one position to another for stopping a portion of the stokermechanism, and means actuated by closure of the access door for causingsaid switch to return to said one position.

4. In a control system for a heating system having a stoker mechanismincluding fuel feeding means for feeding solid fuel to a combustion illchamber, the combination of, means-responsive to the demand for heatfrom the stoker mechanism for placing the fuel feeding means into andout of operation, means including a switch having a first position inwhich the fuel feedin means is rendered operative under the control ofsaid responsive means and a second position in which the fuel feedingmeans is prevented from operating, a member overlying the fuel in thecombustion chamber for moving the switch from its first position to itssecond position when 'the fuel rises to a height indicating the fire isprobably out, an access door for the furnace, manual means for raisingsaid member, latch means for holding said member in its raised positionand means actuated upon closure of said'access door for releasing saidlatch means,

5. In a control system for a heating system having a stokermechanism-includingfuel feeding means for feeding solid fuel to acombustion chamber, the combination otmeans including a controllerhaving a first position in which the fuel-feeding means is renderedoperative and a second position in which the 'fuel'fe'e'ding means isprevented from operating, 'a member overlying the fuel in'the combustioncliamber for moving the controller from its -fi'rs't -po"sitio'n "to itssecond position when the fuel rises to "a predetermined height, andmea'ns including a manually operable controller 'for 'moving said memberand placing said first mentioned 'co'ritroll'er in its secend positionto render the fuel feeding means inoperative. I

6. In a control system for a heating system having a'st'okermechanism'includi'n'g fuel feeding means for feedingsoli'd fu'el to acombustion chamber, the combination of, means including 1 a controllerhaving a first positi'on in which the fuel feeding means is renderedoperative and a second position inwhich the fuel feeding 'mean'sisprevented from operating, a member overlying the fuel in the-combustionchamber for moving the c'ontroll'e'r-fromits first positionto'itsse'cond p'ositio'n when the fuel rises "to a-predete'rminedheight, an access door for the combustion chamber, meansformoving saidmember to place the cont'roller in itssecond position when'th'e-accessdoor is opened thereby permitting access to the combustion chamber withthe fuel feeding mea'ns in nonoperative condition, and meansope'r'ableby closure of said access door to placethe controller in isaid first position.

'7. Ina controlsystem for -a heating system having-a stoker mechanismincluding'fuel feeding'means for feeding solid fuel-to a'combustionchamber, the combination-of, means responsive to the demand for he'atfrom the stoke'r mechanism for placing'the fuelfeeding means into andout of operation, means including "a'controller 12 having afirstposition in which the fuelieedinf. means is'rendered operativeunder the control of said re'sponsive means and a second position inwhich'the fuel feeding means is prevented from operating, a memberoverlying the fuel in the combustion chamber for moving the controllerfrom its first position to its second position when the fuel rises to aheight indicating the fire is probably out, and means for moving saidcontroller to'either its first or second positions irrespective ofthe'position of said overlying member.

3. ,--In a control system for a heating system having a stoker mechanismincluding-fuel feeding means :for "feeding solid'fuel to a combustionchamber, the combination of, means responsive to the demand for heatfrom the st'oker mechanism for placing the fuel feeding means into andout fof operation, means including 'a controllerhaving a-first positionin which the fuel feeding means {is rendered operative under thecontrol-of said vresponsive means and a second position in which thefuel feeding means is prevented from operatioma:member mounted on theWall of the combustion-chamber and-overlying the fuel in'said chamber anaccessdoor for-the combustion chambensaid controller being mountedon'said access 'door, motion transmitting means placing said member incontrol of saidcontroller when the access *door is closed while "causinmovementof i said controller to its 'second'position irrespective ofsaid member when the access door is open, said motion transmitting means'being constructed andarranged to cause movement of the controller toits second -positionlwhen the access door is closed and the member "ismoved by the fuel to a position indicating the fire is probably out. I

.9. 'In a control system for a heating system having a stoker mechanismincluding fuel feeding means for feeding solid fuel to 'a'combusti'onchamber, the combination -of, means responsive to the demandfor heatfrom the stoker mechanism for placing the fuel feeding means 'into andout of operation, means including a controller having a first positionin which'the fuel feeding means is rendered operative 'underthe controlof said responsive means and=a second position in which the fuel feedingmeans is :prevented from operating, an access "door for the combustionchamber, said controller being mounted on the access door, and movablemembermeans extending from said controller through the access door andoverlying the fuel -'in the combustion chamber, said movable membermeans-being constructed andarranged to move the'controller from itsfirst position't'o its second position when the fuel rises toa heightindicatingthat'the fire is probably'out,

HOMER E. MALONE.

